Porous aerogel with aligned hierarchical channels based on chitosan and halloysite for efficient solar steam generation

Solar steam generation (SSG) with efficient interface-evaporation manner has recently emerged as one of the promising approaches to produce fresh water. In this work, halloysite-based SSG (H1) with aligned channels was prepared from halloysite (Hal) and chitosan (CS) by directional freezing and simple carbonization. Then modified the sides and lower surface of H1 to obtain oleophobic generator H2. The as-prepared H1 possess high light absorption (Ca.97.4), excellent thermal insulation (0.086 W m(-1) K-1 in dry state), and abundant porosity (75.6%). Furthermore, the halloysite based evaporator H1 with unique aligned channels can ensure timely water transportation. As a result, leading to a high evaporation rate of 1.58 kg m(-2) h(-1) with an excellent photothermal conversion efficiency of 95.5% under 1 kW m(-2) illumination. In addition, the hydrogel-based evaporation H1 also exhibits superior salt-resistant performance for solar desalination in high concentration brine, and the pu-rified water from artificial seawater can achieve the WHO's standard for ion concentration of drinking water. Moreover, after modification the oleophobic H2 exhibit an excellent evaporation performance in oily water, and can reach to a high conversion efficiency of 86.0%. The halloysite-based evaporation devices have promise to be ideal candidates for efficient SSG and may further expanding the scope of their practical applications.